Flexible, air-tight, collapsible containers for storing and transporting flowable materials such as fluids and finely divided particulate solids such as dry powders and the like have long been used in the transportation and material handling industries. These collapsible containers are typically made of rubber-coated nylon or tire cord fabric and are seen as an excellent way to reduce material handling and shipping costs because they not only provide a sufficient storage container for the flowable materials, but also can be readily transported on flatbed trucks, open railcars, barges, ships or the like. Moreover, because the flowable materials do not change storage containers during shipping, product loss and contamination is substantially eliminated.
Other methods of carrying and/or transporting such flowable materials are typically far more expensive and time consuming. For example, many materials are typically placed in paper bags, cartons or drums and loaded onto skids or other similar liftable devices so that the products can be transported to a particular destination. The process of stacking of the paper bags, cartons and drums on the skids require a significant amount of time and effort. Moreover, the skids used to transport the bags, cartons or drums waste a considerable amount of space. Because of their size and shape, collapsible containers are seen as being capable of carrying more material more efficiently than other types of storage and transportation containers. That is, the space required to store flowable material in a number of paper bags is significantly more than the space required to store the same amount of flowable material in a collapsible container.
While collapsible containers are seen as very useful in the material handling industry, only a small number of flowable materials are actually transported in collapsible containers at present. One of the reasons may be due to the lack of a suitable rubber-coated fabric from which the container can be made. Such a fabric must not only be flexible and air-tight, but also should be extremely durable on the inside, e.g., no chemical deterioration of the fabric, and on the outside, e.g., puncture resistant, friction resistant, chemical resistant, weather resistant, etc. In addition, the fabric should be easy to patch and repair, light weight, relatively long lasting and reusable.
Currently, one of the few known collapsible containers used today in the materials handling industry is available from American Fuel Cell and Coated Fabrics Company of Magnolia, Ark., under the trademark Fabribin. This collapsible container is made of puncture-resistant plies of tire cord fabric which is coated with neoprene and vulcanized into a one-piece, flexible bag. As flowable material is poured into the container, the bag typically expands or conforms to the shape of its environment. Typically, the Fabribin container is cylindrical in shape when not otherwise deformed.
The Fabribin container includes a hook receiving assembly generally positioned at the top of the bag and radially centrally thereof, for hoisting purposes. The hook receiving assembly generally includes a loop for receiving a hook or other means for lifting the container. However, in order to brace the bag from the extreme stresses associated with the lifting of the bag, a plurality of internal cables are positioned within the bag from the centrally-disposed, top hook receiving assembly to the bottom of the bag. These cables permit the weight of the material in the bag to be distributed to the bottom of the bag, thereby causing less stress on the top of the container during the lifting process.
Importantly, when lifting a collapsible container like the prior art Fabribin container, some type of mechanism is necessary to relieve the stresses placed on the point of lifting. Otherwise, due to the type of rubber-coated fabric used, the container could rip, tear or otherwise be damaged. By connecting the internal cables to the bottom of the bag, the Fabribin container provides additional points of lifting, thereby distributing the weight associated with lifting the bag to other pans of the container.
However, the internal cables are not without their drawbacks. In particular, the internal cables necessarily take up space inside the bag, thereby reducing the total available volume of the bag for filling with flowable material. Moreover, the internal cables are difficult to manipulate. Thus, when the collapsible container is to be collapsed, the internal cables may make the collapsing procedure more difficult. Still further, the internal cables have been known to hinder the emptying of the container. That is, certain compactable materials have been known to become wedged or lodged around the cables to such an extent that emptying the container becomes very burdensome.
In addition, the filling and emptying mechanism for the Fabribin container is quite small, thereby requiring substantial time and effort to fill and/or empty the container. Particularly, the fill/empty fitting preferred for the Fabribin container is less than about 6 inches in diameter. Thus, when compactable materials are used in the container, no clumps of material larger than about 6 inches can be emptied from the container. This adds significantly to the labor and handling costs associated with the filling and/or emptying of the container.
The hook receiving assembly employed and placement of the hook receiving assembly at the top center of the bag may also create problems with the Fabribin container such that it may not always function properly as a transportation container in railcars. Moreover, the container itself does not include any mechanism for suspending itself to an up-ender or other device while the container is being emptied.
Therefore, the need exists for a collapsible container having a flexible bag which can be filled, emptied or otherwise used to hold up to at least 20 tons of flowable material. The air-tight, collapsible container should also be capable of being lifted without any internal cables being exposed inside of the container.